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Sunday, 22 February 2015

Why Chomsky might be right about the evolution of language... but probably isn't. Part 1

This is a two-part blog post. Part
1 explains why Chomsky might be right, the second part will explain why I think
he isn’t.

Chomsky says language didn't evolve
- according to psychologist Frederick Coolidge, who recently wrote a blog post
entitled"Why Chomsky is wrong about the
evolution of language."Citing
a2014 paper by Bolhuis, Tattersall, Chomsky
& Berwickas evidence,
Coolidge makes two major claims. First, that Chomsky denies language
evolved, but appeared suddenly and was not subject to natural selection.
Secondly that Chomsky denies genetic evidence, comparative animal studies,
neurophysiological evidence and childhood acquisition theories, all of which
contradict his language origin theory. In this blog post I’ll deal with his
first point and the second in my next post.

I'm a big fan of Coolidge's work in
cognitive archaeology, in particular his collaboration with the archaeologist
Thomas Wynn in their two excellent books: "The Rise of Homo sapiens - The
evolution of modern thinking (2009)" and their more recent volume
"How to Think Like a Neanderthal (2012)." Both books have a
traditional cognitive psychological perspective and are strongly committed to
the ‘mind as a computer’ metaphor, utilising for example a version of Baddeley
& Hitch's model of working memory, complete with concepts such as executive
control. However, they are excellent summaries of archaeological data
(especially for a non-archaeologist such as myself) and they also produce some
intriguing postulations, such as their theory that the transition of our
ancestors from arboreal to terrestrial environments necessitated a change in
sleeping patterns, which could in turn have played a role in imagination and
the creation of new tools (I dream ofelectricstonehand-axes).

On the other hand I'm not a big fan
of Chomsky's theoretical view of language and its origins. His argument that
language must beinnateand that it appeared suddenly and
perfect "like a snowflake," as he said inthis 2012 talk, has seemed to me to be
both outdated and doggedly committed to a rationalist perspective that I instinctively distrust
(let’s not dwell too much on my own contradictions here).

However, having read Chomsky et al.
(2014) paper, I think Coolidge has misrepresented Chomsky's position
somewhat. Chomsky does not deny that language evolved. Indeed the very
first line states the evolution of language is uncontroversial and that the
question ishowlanguage evolved. Chomsky defines
language in this paper extremely narrowly, separating it into two parts. The
first, which he has elsewhere called the broad language faculty (FLB), evolved,
by natural selection, for communicative and social purposes. The second, which
he has elsewhere called the narrow language faculty (FLN), he has reduced to a
single property ofmerge,
which is the mental ability to combine two syntactic elements into a novel set.Mergethen exapted the pre-existing neural
and multi-modal physical architecture of the FLB to give physical expression to
this mental ability, while mappings to the conceptual system gave mental
expression – or a ‘language of thought.’ This would include the ability to form
recursive syntactic structures, but would not necessitate them, handily getting
around the problem of some langauges such as the Piraha apparently not using
recursion. This gave birth to modern humans, culture and everything this
entails.

Natural selection would play an
important role in spreadingmerge,
becausemergeis such a powerful tool, it would have
swept through ancient hominid populations in a similar way to adult lactose
tolerance later sweeping through dairy populations. But the appearance ofmergeitself was sudden in evolutionary
terms and probably the result of a chance mutation.

I’m sceptical about Chomsky’s
definition of language, but if you accept his definition, I think his proposed
evolutionary mechanisms are plausible – and not all that different from Wynn
& Coolidge’s. Furthermore I think some work in embodied cognition supports
this plausibility.

A major point inRoy Pfeiffers lecture on Robotics
was that relatively simple mechanisms can produce very complex and varied
behaviour, as long as the environmental constraints are conducive to this
behaviour. For example, his Robot which walks bipedally, with such a natural
gait, has no power or control mechanisms but must walk in a straight line along
a small incline.

Merge then, could be seen as such a
simple mechanism, which then interacts with the structure and constraints of
the pre-existing hominin communication system, including the rest of the
organism, other organisms, the physical environment, to produce fully modern
representational thought and language. I’m not arguing that Chomsky has an
embodied perspective here (he most certainly does not!), I’m just arguing that
the principle of complex behaviour resulting from simple mechanisms could be
applicable to his view of language and that applicability makes it more
evolutionarily plausible than Coolidge gives credit for, because Chomsky is
actually postulating the sudden appearance of a simple, rather than a complex
mechanism.

In light of all this, why then does
Coolidge claim Chomsky doesn’t think language evolved? I think part of the
problem might be they have different understanding of what is meant by
evolution. Coolidge appears to have a fairly standard ‘gradualist’ perspective
on evolution and his theory on the evolution of the human mind is a detailed
account of gradual change, containing multiple stages. Complex organs, like
complex behaviours do not simply pop into existence, whether it is the
complexity of an eye or a lung, the ability to make an Acheuleun handaxe or
hold a conversation. They must have had transitional forms and these forms were
shaped by natural selection.

Chomsky, however, relies heavily on
the ideas of Gould/Lewontin (indeed, Lewontin is one of Chomsky's collaborators
on other papers), who emphasised the importance of exaptation, where a feature
which evolved for one purpose, is utilised for another. Feathers are a classic
example, originally evolving for heat regulation, then exapted for flight.
Natural selection is still central in this view, but it is not the only force
shaping change, with genetic drift and chance playing a greater role.

In fact, Coolidge has proposed
similar mechanisms in his own work. In their book: "The Rise of Homo
sapiens - The evolution of modern thinking (2009)," Wynn & Coolidge postulate that
the final major advance in modern human cognition was a mutation which
increased working memory and enabled advanced executive functioning. They argue
this small change resulted in a series of complex changes including advanced contingency
planning and a transition from symbols used as markers, to the emergence of
fully modern symbolic thought, as evidenced by the archaeological discovery of
complex figurines. Is this so different, in terms of evolutionary plausibility,
from Chomsky’s proposed emergence ofmerge?

However, although Chomsky's theory
on the evolution of language is plausible I don’t think it's correct, for
reasons I will elucidate in my next post.

Thanks Fred, that’s an interesting paper and it makes some powerful points about the nature of inner speech and how it is not simply an internal homolog of vocal speech. I think Chomsky's Minimalist Thesis is flexible enough (some might say slippery enough) to survive some of these objections, but it’s given me a couple of good ideas for my next post.